What is this

[Tristenvadv]

Hey I just got a fish tank and it came with this white thing with little slits in it what is it?

[Brookster123]

Saltwater setup? Could be for sump filtration or a coral grow tray??

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[Tristenvadv]

Freshwater setup

[Just Another Fish Guy]

That looks like part of an under gravel filter.

[troyd75826]

That is undergravel filter, useless without the riser tubes which connect to it

[Just Another Fish Guy]

Time to invest in either a HOB or canister filter!!

[treemanone2003]

I saw one of those. Somewhere around 1990.

[Redwolf91]

Under gravel tray, pretty much useless IMHO

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[PB_Smith]

Seriously???
When properly maintained, undergravel filters work great and utilize the entire surface area of the substrate as filter media.
All the horror stories I've heard have to do with too deep of a substrate bed, using too fine or too coarse of a substrate and improper maintenance.

How many of you saying they are useless have ever actually utilized one?
In reality they can offer more stability than I have seen in more "modern" and "high-tech" methods, you just have to keep it cleaned and maintained, like any other system.

[Redwolf91]

Used them in fw for a good while (granted, this was over twenty years ago) but got tired of having to move everything to maintain under them. Like I said, just IMHO, but I'd never bother with one again

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[PB_Smith]

Originally Posted by Redwolf91

Used them in fw for a good while (granted, this was over twenty years ago) but got tired of having to move everything to maintain under them. Like I said, just IMHO, but I'd never bother with one again

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Really, I would just stick the siphon hose down the lift tubes about every3-4 water changes and suck any detritus under the plate out. No need to dismantle everything.
Conversely you can use them in a reverse flow configuration and that greatly reduces the amount of detritus that accumulates in the substrate/under the plate.

In my experience they are more stable than canister or HOB filters and are much more forgiving in terms of inconsistent feeding/bio-load.
You can overwhelm or kill off a canister, HOB, or even a sump system much faster and easier than you can an under-gravel.
The greatest drawback to them is the same as most biological filter systems, they are not that great at breaking down nitrate. Even with all the new tech, nitrates still pose a problem.
Luckily with the increase in knowledge concerning the biological process involved, we have come up with refugiums, de-nitrification filters and de-nitrification media.

As far as being a "nitrate factory", that happens with any type of filter that has the water passing through the media if not properly maintained.

[Redwolf91]

Very true on maintenance, I run a scrubber and skimmer on my150, params always stay good, so I'm sticking with what's working for me now

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[mattcham]

Is nitrate really ever a problem if regular water changes are performed?

Anyway, I just came back to the hobby 4 months ago after a 20 year break. I was surprised to see that undergravel filters have gone extinct. I thought the power heads made them work very well compared to the original airstone-driven design.

[Delapool]

Originally Posted by mattcham

Is nitrate really ever a problem if regular water changes are performed?

Anyway, I just came back to the hobby 4 months ago after a 20 year break. I was surprised to see that undergravel filters have gone extinct. I thought the power heads made them work very well compared to the original airstone-driven design.

Lol - I missed the power heads and only used the air stone driven ones. A favourite place for suckling catfish to disappear in to. Now running canister filters.

I've found every so often I just have to clean the canisters as nitrates is creeping up. I hate doing it and run two just to avoid it partly but cleaning tends to halve my nitrate level.

[PB_Smith]

Originally Posted by mattcham

Is nitrate really ever a problem if regular water changes are performed?

Anyway, I just came back to the hobby 4 months ago after a 20 year break. I was surprised to see that undergravel filters have gone extinct. I thought the power heads made them work very well compared to the original airstone-driven design.

Yes, if detritus and junk are allowed to accumulate, then it can produce a "nitrate factory"

I wonder the same about UG filters and have as of yet not gotten any really sound, reasonable reasons as to why.

I will always utilize one in some fashion. With proper maintenance, they are great and I have "saved" tanks of fish before with an under gravel and battery operated air pump, can't do that with a canister or sump system alone.

The best implementation of an under gravel filter would be a reverse flow configuration with a moderate flow rate combined with other means of filtration, either canister or sump. That way the UG should be able to maintain the bio-load in the event of filter failure (ug filters essentially can't "fail") or maintenance. Having it a reverse flow reduces the amount of detritus that accumulates on/in the substrate and reduces one of the sources of nitrates with ug filters.

But I am open minded, if someone can provide me with sound scientifically based info as to why UG filters are no longer promoted, (poor maintenance isn't a valid reason) then I will reconsider my position, but I can't think of any solid arguments against their use.

[mattcham]

The problem I can see with UG filters is that it's like having a filter whose media you cannot clean (due to plants and decor for example). Regular water changes do not replace the need to clean filter media, which in this case is the uncleanable sand or gravel beneath your plants stones and driftwood.

[PB_Smith]

how do you clean those areas of your tank now? detritus and junk still collects in those areas if you don't move stuff and clean up.

Under gravel filters are usually not recommended for planted tanks, although I have had very successful planted tanks with ug filters before.
Other than that, a routine cleaning and moving décor really only needs to be done 3-4 times a year, not unreasonable.
Plus you don't really want to "clean" the substrate much more than using a gravel vac at water changes and as I stated, using a reverse flow greatly minimizes the amount of detritus that accumulates.


So again, it comes down to simple maintenance.
Still waiting to hear some sound science behind the abandonment of the technology.

[mattcham]

Originally Posted by PB_Smith

how do you clean those areas of your tank now? detritus and junk still collects in those areas if you don't move stuff and clean up.

Well, that's the main argument favoring sand over gravel. With sand, the dirt does not slip deep into your aquarium floor, unless you have an UG filter pulling (or pushing) things into the sand.

[Delapool]

In my view a canister filter can be taken apart and cleaned readily. I run two and I can totally clean one at a time. So I can readily remove all debris and keep nitrates low. I can run purigen or carbon or all sorts of combinations.

From my experience an ugf is not as easy to clean and remove debris.

In ammonia terms I don't think much difference. I have say 40 kilos of gravels versus say 7 kilos of ceramic biomedia.

I think it comes down to nitrates. If your nitrates are low with an ugf why change? If they are high with an ugf than a canister filter I would swap to. My thoughts on an interesting discussion.

[PB_Smith]

Originally Posted by mattcham

Well, that's the main argument favoring sand over gravel. With sand, the dirt does not slip deep into your aquarium floor, unless you have an UG filter pulling (or pushing) things into the sand.

Yet you still do utilize a gravel vac when doing routine maintenance like the majority of people, correct? so what's the difference?
Part of maintaining an ug filter is in using the proper grain size(s).

So it is still a question of the degree of maintenance a person wants to put into a system, not any failing of under gravel filter technology per se.